Effectiveness, Implementation and Spillover Effects of a Culturally Adapted DPP in Spanish Primary Care Centers

Effectiveness, Implementation and Spillover Effects of a Culturally Adapted Diabetes Prevention Program in Spanish Primary Care Centers: a Cluster Randomized Hybrid Type II Trial

The ALADIM trial is a hybrid type II effectiveness-implementation cluster-randomized controlled, parallel, two arm, superiority trial. The clusters consist of 10 Primary Care Centers (PCCs) of Mallorca (Balearic Islands, Spain), which are randomly assigned to either the intervention or the control group in a 1:1 ratio. The intervention group (5 PCCs) receives training and supporting material to facilitate the implementation of the adapted DPP and effectively deliver the program over a 12-month period. The control group (5 PCCs) continues providing usual care, in line with standard healthcare practices. Effectiveness outcomes are assessed at participant level according to a cluster-randomized controlled design with data collection at baseline, 6-month and 12-month during the intervention period, and at 18-month follow-up to evaluate mid-term effects post-intervention. Implementation outcomes are assessed at PCC level throughout the study period. Prior to the hybrid trial, the DPP will be culturally and contextually adapted to the Spanish Primary Care setting.

The DPP will be culturally adapted using the Intervention Mapping ADAPT (IM-ADAPT) approach. Simultaneously, the implementation strategy will be designed using the Implementation Mapping approach.

Alongside type 2 diabetes (T2D), prediabetes prevalence is also rising, placing a significant burden on public health systems, individuals, and their families.

Promoting a healthy lifestyle that includes regular physical activity, a healthy diet, smoking cessation, and achieving and maintaining a healthy body weight can effectively prevent or delay T2D onset. Major diabetes prevention trials, such as the Diabetes Prevention Program (DPP) in the United States, have demonstrated that intensive lifestyle interventions can significantly reduce T2D risk in individuals with prediabetes.However, despite strong evidence supporting the effectiveness of lifestyle interventions, and international guidelines recommending screening and referral of at-risk individuals, the global impact of scaling up diabetes prevention in real-world healthcare practice remains insufficient, most probably due to systemic (organization and leadership) and individual (healthcare professionals) barriers hindering effective implementation.

The ALADIM study aims to evaluate the effectiveness and implementation of an adapted DPP in Spanish Primary Care Centers (PCCs), using a hybrid type 2 approach. This approach addresses the gap between efficacy and effectiveness studies, providing clinically valid results while accelerating the translation of research into practice. The IM-ADAPT approach will guide the DPP adaptation to the Spanish Primary Care setting, while Implementation Mapping will inform the development, refinement, and evaluation of the implementation strategy.

Inclusion Criteria:

Age ≥18 years; body mass index (BMI) of ≥25 kg/m2 (≥23 kg/m2, if Asian); fasting plasma glucose (FPG) between 1010 and 125 mg/dL, or plasma glucose of 140 to 199 mg/dl measured 2 hours after a 75 g glucose load, or HbA1c between 5.7% and 6.4%, or with a documented history of gestational diabetes mellitus during a previous pregnancy.

Exclusion Criteria:

Previous diagnosis of type 1 or type 2 diabetes; current use of antidiabetic medications; pregnancy at time of enrollment; terminal illness; institutionalization; dementia or significant cognitive impairment; major surgery or hospitalization in the previous 3 months; presence of any medical or psychological condition limiting participation; and concomitant active participation in another clinical trial.